A number of different retaining systems have been devised for preventing eyeglasses from slipping or falling off. Some of these systems rely on resilient straps to hold the eyeglasses securely on the wear's head during sports and other physical activities. Some strap systems may permit limited adjustability of the strap tension by means of a buckle, hook and loop fasteners, or by allowing the user to adjust the point of attachment to the eyeglass temple bars. Other eyeglass retention systems rely on single lengths of cord or tubular material that are attached to the temple bars. The materials used in the retaining cords and tubes, and the elasticity of those materials, vary considerably. Some of the retention systems that use cords and tubes, unlike the systems that use flat straps, use a long cord with a slider that frictionally engages the doubled cord behind the head. The slider allows the user to adjust the cord tension and to release it entirely in order to lower the eyeglasses to hang loosely below the neck and at a preferred distance below the neck.
A problem encountered by all of the prior art eyeglass retention systemsconcerns the means of attaching the retention straps, cord or tubing to the eyeglass temple bars. Some eyeglass retention systems rely on sleeves that slide over the end of the temple bar, as shown in U.S. Pat. No. 5,575,042 to Kalbach (1996). Sleeves that fit over the portion of the temple bar in front of the downwardly curving section of the temple bar are shown in U.S. Pat. No. 4,133,604 to Fuller (1979), U.S. Pat. No. 5,157,425 to Liu (1992), and U.S. Pat. No. 5,087,118 to Gill (1992). A number of systems rely on elastomeric rings and loops of various configurations that are attached to each end of a retainer cord and frictionally engage the temple bars. Examples of such systems are disclosed in U.S. Pat. No. 3,874,776 to Seron (1975), U.S. Pat. No. 4,790,646 to Seron (1988), U.S. Pat. No. 4,965,913 to Sugarman (1990), U.S. Pat. No. 5,092,668 to Welch, et al. (1992), U.S. Pat. No. 5,655,264 to Davancens, et al. (1997), and U.S. Pat. No. 5,805,262 to Deveney (1998). Other systems employ loops that are formed in the end of the retainer cord and are tightened around the temple bar by pulling the cord through a sleeve, as shown, for example, in U.S. Pat. No. 3,827,790 to Wenzel (1974), and U.S. Pat. No. 4,783,164 to Heiberger (1988). U.S. Pat. No. 5,507,075 to Tillstrom (1996) discloses a loop/spring combination whereby the loop is held onto the temple bar by the compression of the spring.
Another method of attaching a retention cord to the temple bars is disclosed by U.S. Pat. No. 5,786,882 to Satterthwaite (1998), which shows eyeglass temple bars with forward-facing slots in the ends of each temple bar that engage a continuous elastic band, such as a rubber band, or each end of a single length of elastic band material. U.S. Pat. No. 4,603,951 to Beck, et al. (1986) shows an eyeglass frame with a hole at the end of one temple bar and a longitudinal opening in the end of the other temple, so that an elastic band can be inserted through the holes, with an enlarged end of the cord engaging the hole in the first temple and the other end engaging the longitudinal opening in the second temple in a self-locking manner. U.S. Pat. No. 4,761,068 to Star (1988) shows two retaining straps having hook and loop fasteners on one end and mushroom-shaped tips on the other end that are inserted through holes in the temple bars and secured with small C-shaped clasps. A different approach is disclosed in U.S. Pat. No. 4,976,531 to Kahaney (1990), which shows a strap assembly that, in one embodiment, snaps into suitably-sized holes in the end of each temple bar.
U.S. Pat. No. 3,728,012 to Downey (1973) discloses an eyeglass retention system wherein the retaining strand is a plastic monofilament line that passes behind the head and through openings in the temple bars. The strand is tensioned by pulling one or both of its ends, and the high friction of the strand against the openings holds the eyeglasses in the desired position. U.S. Pat. No. 5,655,263 to Stoller (1997) discloses a retaining cord with ends that pass outwardly through holes in each temple, with each end then being inserted through a friction block and knotted. The eyeglasses can be held snugly against the face by pulling each end knot laterally and moving the friction blocks against their respective temple bar, with the result that the cord ends hang down on both sides of the neck behind the ear. To lower the eyeglasses, the friction blocks are moved toward the ends of the cord. This system also calls for the cord to have sufficient surface texture to hold the eyeglasses at the desired level below the neck by the friction of the cord against the inside surface of the holes.
Yet another approach to securing the retainer cord to the temple frames is shown in U.S. Pat. No. 5,917,576 to Falco (1999), which discloses a retaining band comprised of a single length of polymeric material that is bonded to the end of each temple bar. The polymeric retaining band can be permanently stretched by the user to customize its length within the elongation limits of the material. U.S. Pat. No. 5,541,676 to Pallat (1996) eliminates the temple bars altogether and shows the retainer cords being attached to the temple bar hinges on the each side of the front lens-containing portion of the eyeglass frame. U.S. Pat. No. 5,926,855 to Brodbeck (1999) shows a system for securing goggles of the type used by swimmers that involves threading a single length of elastic shock cord through a hole on each side of the goggle, and then inserting the ends of such single cord through a spring-loaded cord lock. This arrangement results in a double strap system around the back of the head and permits strap tension to be adjusted by moving the cord lock.
There are a number of disadvantages and limitations associated with the retaining systems disclosed by the prior art, particularly where extended-wear comfort, appearance, and manufacturing cost are all important considerations. The goggle-type bands and straps are well suited for applications where a snug fit over short periods is required, but they tend to be too tight and uncomfortable for extended or casual wear. These strap systems also do not allow the eyeglass to be lowered to hang on the chest, as do some of the adjustable cord retainer systems. However, the braided cords and tubular bands typically used in adjustable cord systems can feel heavy and bothersome on the neck and shoulders.
Furthermore, the means disclosed by the prior art for attaching the retaining systems to the temple bars also have significant drawbacks. The attachment rings and sleeves that fit over the temple bar can affect the way the temple bar feels as it passes over and behind the ear, and thus can be annoying to many eyeglass wearers. The elastomeric rings can be pulled off inadvertently if they have not been tightly secured or if the temple bar lacks a substantial flare at the end to help keep the ring on the bar. A number of popular sunglass styles have a sleek, minimalist appearance with narrow temple bars that have very little, if any, flare at the end. The prior art eyeglass retainers with enlarged ends that engage holes in the temple bars have the significant limitation of not working with holes that exceed a certain maximum size. Eyeglass retainer systems that adjust by pulling the ends of the retainer strands laterally from the temple result in unsightly and bothersome strand ends hanging down behind each ear. Furthermore, the complexity of some retention systems renders them impractical from a manufacturing cost standpoint.